Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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Preliminary Close Out Report
Imperial Refining Superfund Site
Ardmore, Carter County, Oklahoma
(CERCLIS ID OK0002024099)
United States Environmental
Protection Agency
Region 6
Superfund Division
September 18, 2008
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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I. Introduction
The U.S. Environmental Protection Agency (EPA) has completed this Preliminary Close Out
Report for the Imperial Refining Superfund Site (Site) in accordance with the Close Out
Procedures for National Priorities List Sites, OSWER Directive 9320.2 – 09A-P, and in
recognition of the completion of the remedy construction consistent with the Record of Decision
(ROD). This determination is based on review of Site data, field inspections and oversight, and
three pre-final inspections (August 6, 2008; August 13, 2008; and September 10, 2008)
conducted by the Oklahoma Department of Environmental Quality (ODEQ) and the EPA. The
Site remedy construction was accomplished pursuant to, and in accordance with, the
requirements of the Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA), 42 U.S.C. § 9601 et seq., and consistent with the National Contingency Plan (NCP),
40 CFR Part 300. The EPA and ODEQ have initiated the activities necessary to achieve the
cleanup levels and site completion.
II. Summary of Site Conditions
Background
The Imperial Refining Company (IRC) Superfund Site is the location of a former petroleum
refinery that operated from 1917 to 1934. The legal description for the property is SE ¼, NE ¼,
Section 20, and SW ¼, NW ¼, Section 21, T4S, R2E, Indian Meridian, which is located within
the northeastern portion of the City of Ardmore, Carter County, Oklahoma. The IRC Site is
divided into three parcels: the West (36.5 acres), East (14.5 acres) and East Railroad (21 acres).
The Site covers approximately 72 acres and is bisected by U.S. Highway (Hwy) 142 and railroad
tracks operated by the BNSF Railway Company (Figure 1). Numerous tanks and buildings were
present on the Site during refinery operation, but all of the tanks and most of the buildings were
dismantled sometime between 1934 and 1948 leaving the property in much the same condition
as it is in today, mixed wooded areas and open fields.
The adjacent property to the north and east of Hwy 142 is occupied by a facility that
manufactures roofing shingles. Waste-water processing lagoons operated by Valero Refining are
located west of the Site, and the rest of the immediately adjacent property is largely
undeveloped. Several small businesses, Valero’s active refinery, and a small residential area with
about a dozen houses (along the streets of Brooks, Akron, Commerce and Industrial) are located
within ¼ mile north of the Site. An estimated 23,000 people live within a 4-mile radius of the
Site.
The IRC began operations at the Site in 1917. The eastern portion of the property was purchased
in April 1917, and the western portion was purchased three months later. IRC remained active
for 17 years until it went bankrupt in 1934. Due to the absence of environmental regulations
during the operational period of IRC, no permits, violations, inspections, or facility operation
documentation have been identified, and no records have been found that describe the types of
activities that took place on the Site. Currently, the land is privately owned, and no commercial
activities are taking place.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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Preliminary Investigations
The ODEQ conducted a Preliminary Assessment in September 1997 and a Site Inspection in July
1998. Based on the results, elevated levels of benzene, ethylbenzene, toluene, xylenes and
polycyclic aromatic hydrocarbons were present. ODEQ referred the property to the EPA for
further action.
Removal Actions
Subsequent to the ODEQ investigations, EPA conducted a Removal Assessment in 1998 to
determine the absence/presence of hazardous materials and the types and concentrations of
hazardous substances followed by a second Removal Assessment in 1999 to estimate waste pile
volumes and evaluate disposal options. A Removal Action to install a perimeter fence was
conducted from June 29, 2004, through July 23, 2004.
The Site was proposed to the NPL on May 11, 2000, [Federal Register: May 11, 2000 (Volume
65, No. 92, Page 30489-30495)] and was finalized on July 27, 2000 [Federal Register: July 27,
2000 (Volume 65, Number 145, Page 46096-46104)].
Remedial Investigation/Feasibility Study
The EPA and ODEQ negotiated a Cooperative Agreement under which the ODEQ was the lead
agency for the Remedial Investigation/Feasibility Study (RI/FS) with EPA acting as the
supporting agency. From early 2005 through early 2007, contractors for the ODEQ conducted a
RI/FS including field sampling and investigation activities of soil, sediment, surface water,
ground water, and animal tissue. The Remedial Investigation and Feasibility Study reports
identified the types, quantities, and locations of contaminants found in these samples and
developed ways to address the contamination. In addition, a Human Health Risk Assessment
and an Ecological Risk Assessment were performed to determine the current and future effects
of contaminants on human health and the environment.
Onsite contamination includes waste material, soil and sediment. Arsenic and benzo(a)pyrene
are the primary contaminants of concern. The primary sources of contaminants are waste in an
underground storage tank and waste piles characterized as dry, asphalt-like material. The waste
material is found throughout the Site, and the benzo(a)pyrene concentrations range from 2.5
milligram per kilogram (mg/kg) to 570 mg/kg. In addition to the waste material, surface soil [0-
1 foot (ft) below ground surface] and sediment (0-1 ft below ground surface) have elevated
concentrations of benzo(a)pyrene and arsenic. The soil concentrations range from 1 mg/kg to 90
mg/kg for arsenic and 0.04 mg/kg to 10.2 mg/kg for benzo(a)pyrene. Sediments in onsite
intermittent drainages are indistinguishable from Site soils except by their location within
drainages; therefore, the drainage sediments are considered soils for the remedial action as these
remain dry most of the year.
Record of Decision
After review and response to comments, the Record of Decision was signed on December 26,
2007. Remedial Action Objectives (RAOs) were developed for Site soil, sediment, and waste
material and are listed below.
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Surface Soil
• Prevent exposure to current and future human and ecological receptors through ingestion,
dermal contact, and inhalation of contaminated soil containing arsenic and benzo(a)pyrene
concentrations in excess of 5E-05 and 2.5E-05 excess cancer risk, respectively.
Pond and Creek Sediment
• Prevent exposure to current and future human receptors through ingestion, dermal contact, and
inhalation of contaminated sediment containing arsenic concentrations in excess of 5E-05 excess
cancer risk.
• Prevent exposure to current and future ecological receptors through direct contact, foodchain
uptake, and incidental ingestion of contaminated sediment containing benzo(a)pyrene
concentrations in excess of levels that are protective of ecological receptors.
Waste Material
• Prevent exposure to human and ecological receptors through ingestion and dermal contact.
• Prevent further migration of waste material contamination.
In order to achieve these RAOs, numerical risk-based cleanup levels were established for each
environmental medium based on the residential scenario:
The ROD addressed the Site as one operable unit where the final response action will address
Site contaminants and waste material through the following:
Table 1 – Cleanup Levels for Contaminants of Concern under a Residential Scenario
Media: Soil
Site Area: West and East Parcel
Available Use: Residential
Chemical of Cleanup Level Basis for Cleanup Level Risk at Cleanup Level
Concern
Arsenic 20 mg/kg Background level 5.00E-05
Benzo(a)pyrene 1.55 mg/kg Human Health Risk
Assessment 2.50E-05
Media: Sediment
Site Area: East and West Ponds, Sand Creek
Available Use: Residential
Chemical of Cleanup Level Basis for Cleanup Level Risk at Cleanup Level
Concern
Arsenic 20 mg/kg Background level 5.00E-05
Benzo(a)pyrene 0.782 mg/kg Ecological Risk Assessment
Invertebrate Toxicity Test
N/A
Results
Note: mg/kg: milligrams per kilogram
N/A: Not Applicable
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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• 13,083 yd3 of waste material will be removed and disposed offsite at an appropriately regulated
facility based on results from toxicity characteristic leaching procedure (TCLP) analyses. This
addresses the principal threat waste at the Site.
• 16,438 yd3 of arsenic and benzo(a)pyrene contaminated soil will be excavated and disposed
offsite at an appropriately regulated facility based on results from TCLP analyses.
• 1,633 yd3 of arsenic and benzo(a)pyrene contaminated sediment will be excavated and disposed
offsite at an appropriately regulated facility based on results from TCLP analyses.
The remedial action set forth in the ROD was consistent with, and complied with, the Superfund
Amendments and Reauthorization Act (SARA) of 1986, P.L. 99-499, which substantially
amended CERCLA, 42 U.S.C. § 9601 et seq., and the NCP. SARA codified many of the
existing requirements under the then existing NCP (1985), as well as adding, among other
things, a new Section 121 to CERCLA, which provided direction for selection of remedial
actions compliant with applicable or relevant and appropriate Federal, State, and Local laws
regulations and requirements, 42 U.S.C. § 9621.
Based on the investigation of Site historical information, one potentially responsible party (PRP)
was identified. EPA and the PRP negotiated and signed an Administrative Order on Consent
based on Ability-to-Pay Analysis (September 15, 2004). The Site remedial action was completed
as an EPA fund-lead project, with the ODEQ as the support Agency.
Remedial Design
A detailed remedial design was not performed due the simplicity of the selected remedy. A
value engineering evaluation and the remedial design and remedial action work plan were
completed on January 30, 2008. During work plan development, additional field activity was not
considered necessary as the extent of waste was presumed to be known.
Remedial Construction Activities
The EPA began onsite RA construction February 13, 2008. As excavation of the waste material
began and continued into the following weeks, it became clear that the vertical and horizontal
extents were understated, and the original volume estimate was low. Although, the expectation
was to exceed the original volume estimate, attempts were made to meet the residential cleanup
values. As excavation activities progressed, waste was found to exist in locations where removal
would be both impracticable and dangerous. Due to the increase in horizontal and vertical extent,
increase in volume, and locations where waste will be left in place, aspects of the original
remedy were reevaluated and are described below. These changes will be documented in a
Record of Decision-Amendment.
Cost
The original cost estimate to implement the remedial action described in the ROD was $4.4
million (net present worth). Costs were estimated at a discount rate of 7% with no operation and
maintenance (O&M) or five-year reviews. Due to the increase in waste volume, a revised cost
estimate for the project is projected to be $6.8 million. The difference between the ROD
estimate and the revised cost estimate is due to the increased costs associated with the increased
volume of waste material excavated and disposed offsite as well as the inclusion of backfill
material necessary for Site restoration and grading. In addition, five-year reviews and O&M will
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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be required and the estimated cost, projected for a timeframe of 30 years is $179,131.47. A
complete breakdown of the final costs and details related to O&M activities will be presented in
the final Remedial Action Report and the final O&M Plan.
Volume
Refinery wastes were encountered at depths up to 10 feet below ground surface and in locations
not previously identified during the Remedial Investigation. Therefore, the discovery and
excavation of these new locations increased the volume of waste material disposed. Because
these were defined as principal threat wastes, excavation and disposal was necessary to eliminate
the wastes as a source of contamination for soil, sediment, surface water, and ground water as
well as eliminate the threat to human health and the environment. It is expected that the volume
of material excavated and disposed offsite will reach an estimated 104,493.5 cubic yards
(yd3)/105,770.76 tons which represents an increase of 74,972.5 yd3/55,954.76 tons over the
estimated 29,521 yd3/49,816 tons presented in the December 26, 2007, Record of Decision
(ROD). A complete breakdown of the final volume will be presented in the final Remedial
Action Report.
Cleanup Values
The cleanup scenario presented in the ROD is based on the child resident. When the industrial
and residential soil scenarios were compared, it was noted that cleanup to a residential scenario
minimally increased soil volume (690 yd) and cost ($252,068); it would result in unlimited use
and unrestricted exposure; and would be protective for all other human and terrestrial ecological
receptors. Therefore, in order to be protective for Site reuse under a residential scenario and
meet the RAOs, cleanup levels in the ROD were established for the primary contaminants of
concern, arsenic (5E-05 excess lifetime cancer risk) and benzo(a)pyrene (2.5E-05 excess lifetime
cancer risk).
The widespread extent, depth, and location of the waste material discovered across the Site
during the remedial action have made excavation impracticable and potentially dangerous in
some areas. Because of this, waste material will be left in place (see sub-section Waste Left in
Place), which makes the residential scenario no longer suitable for this Site.
Current and future zoning maps produced by the City of Ardmore depict portions of the Site
west of Hwy 142 and east of the railroad tracks as light industrial and the portion of the Site east
of Hwy 142 and west of the railroad tracks as heavy industrial. The human health risk
assessment evaluated risk for the industrial worker and showed that the excess lifetime cancer
risk for an industrial worker fell within the risk range of 1E-04 to 1E-06 and the non-carcinogenic
risk was less than 1. The excess lifetime cancer risk is primarily associated with
the ingestion and dermal contact pathways related to arsenic and benzo(a)pyrene in the soil and
sediment. Because the exposure pathways and contaminants of concern are the same as those
identified for the future child resident, the RAOs presented in the ROD remain unchanged.
Therefore, changing from a residential scenario to an industrial scenario is protective, and in
order to meet the RAOs under an industrial scenario, revised cleanup levels were established.
In the absence of Federal or State cleanup standards for soil contamination, the Site cleanup
levels are based on the baseline risk assessment. The arsenic cleanup level remains set at 20
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
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mg/kg which is within the range for Oklahoma background soils, represents an excess upper
bound lifetime cancer risk to an individual of 5E-05 which is within EPA’s cancer risk range of
1E-06 to 1E-04, is below the non-cancer benchmark of 1, and is considered protective of human
health and the environment. Using all assumptions and calculations presented in the human
health risk assessment, the cleanup level for benzo(a)pyrene (2.5E-05 excess lifetime cancer
risk) under an industrial reuse scenario is 5.27 mg/kg, and is considered protective of human
health and the environment. Despite the change in the cleanup level, these risk drivers remain
co-located with other metals and organics as well as areas of ecological risk associated with the
upland habitat (soil) and wet areas (sediment not in the ponds or creek); therefore, revision of the
ecological cleanup levels is not necessary.
Because the Site will be restricted to industrial use and is not available for unlimited use and
unrestricted exposure, institutional controls, O&M, and five-year reviews will be required.
These activities are applicable to the entire Site. Details related to these activities are described
below.
Waste Left in Place
The widespread extent, depth, and location of the waste material discovered across the Site
during the remedial action have made excavation impracticable and potentially dangerous in
some areas. Excavation and removal activities have progressed to the extent practicable;
however, there will be areas where waste remains. This material has been identified as a non-hazardous
waste. In addition, TCLP data indicate that the leaching potential of this material is
low as all results have been below regulatory limits for characteristic hazardous waste categories
and land disposal restrictions. As such, backfill of the excavated areas and areas above the waste
material provides for slope control, drainage control, and establishment of vegetation.
a. Ponds: All surface sediments that exceeded the ecological cleanup level have been
excavated and confirmation samples have been collected. The confirmation sample results are
below the ecological cleanup level. Based on excavation activities along the drainages and shore
lines, waste was documented at depths greater than 18 inches and extending out into the ponds.
Additional delineation pits were excavated within the east and west ponds to identify the extent
of the waste. The delineation pits indicated that the waste is widespread and continued to be
present under at least 18 inches of uncontaminated overburden. The presence of the overburden
and its thickness is expected to act as a barrier between the waste and the surface sediments as
well as provide ample non-contaminated burrowing material above the waste for benthic
invertebrates. This is supported by the surface sediment results from the remedial investigation
and those confirmation samples collected during the remedial action. In addition, erosion and
scouring of the overburden is not expected as these ponds are stagnant for most of the year and
high flow velocity currents are rare. Due to the presence of uncontaminated overburden, the
complete removal of surface sediment exceeding the ecological cleanup numbers, and the
unknown locations of waste at depth throughout the remaining areas of the ponds, no further
excavation will occur. Excavated areas will be backfilled with clean material and an institutional
control (IC) will be placed on the ponds. Operation and maintenance activities will be conducted
by ODEQ and five-year reviews will be conducted by EPA to ensure protectiveness.
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b. Northern boundary with Atlas Roofing: The northern boundary of the eastern parcel is a
slope approximately 10 to 15 feet in height. Atlas Roofing, Inc., is built on the land at the top of
this slope. Excavation activities along this border indicate that waste materials extend into this
slope; the exact extent is unknown. Excavation and removal of waste along this border is not
feasible or practical as this may alter the stability and integrity of the slope. An engineering
evaluation identified suitable slope stabilization and construction activities and an appropriate
backfill material for placement on the waste. A slope of no greater than 3 feet vertical to 1 foot
horizontal will be maintained along this border to minimize erosion and facilitate slope support,
drainage control, and re-vegetation. Atlas Roofing will place an institutional control on the Atlas
Roofing, Inc., property. Operation and maintenance activities on the slope will be conducted by
ODEQ in coordination with Atlas Roofing, Inc. Five-year reviews will be conducted by EPA to
ensure protectiveness.
c. Hwy 142: The situation is similar to the northern border with Atlas Roofing, Inc. The
highway sits atop a slope approximately 10 to 15 feet in height. Excavation activities along the
eastern and western borders of Hwy 142 indicate that waste materials extend into this slope and
under the highway exposing itself on the opposite side. Excavation and removal of waste along
these borders and under the highway is not feasible or practical as this may alter the stability and
integrity of the slope and the highway. An engineering evaluation identified suitable slope
stabilization and construction activities and backfill material for placement on the waste. A
slope of no greater than 3 feet vertical to 1 foot horizontal will be maintained along this border to
minimize erosion and facilitate slope support, drainage control, and re-vegetation. The
Oklahoma Department of Transportation (ODOT) will place an institutional control on Hwy 142
and its associated utility easements. Operation and maintenance activities on the slope will be
conducted by ODEQ in coordination with ODOT. Five-year reviews will be conducted by EPA
to ensure protectiveness.
d. Northern and Western Boundary with Valero Refinery property: During excavation
activities, it was determined that waste extends across the shared western and northern property
boundaries with Valero Refinery. ODEQ’s Resource Conservation and Recovery Act (RCRA)
section will be working with Valero Refinery to address the waste along these borders. Backfill
of the excavated areas and areas above the waste material provides for slope control, drainage
control, and establishment of vegetation. The drainage along this boundary will be re-directed
away from these waste areas in an effort to mitigate erosion, ensure drainage control, and
facilitate re-vegetation. Operation and maintenance activities on the Imperial Refinery side of the
property will be conducted by ODEQ. Five-year reviews will be conducted by EPA to ensure
protectiveness.
e. Oneok Gas Line: Excavation in close proximity to the high pressure gas line was not
recommended or considered safe; therefore, waste was left around the gas line and within the
easement boundaries. Clay backfill was placed on either side of the pipeline and a depth of
approximately two feet, was placed along the top of the gas line to provide a barrier for the
pipeline and promote surface water runoff. A gentle slope will be maintained along this border
to minimize erosion and facilitate slope support, drainage control, and re-vegetation. An
institutional control will be placed on the Oneok easement as part of the Imperial Refining Site.
Operation and maintenance activities will be conducted by ODEQ in coordination with Oneok.
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Five-year reviews will be conducted by EPA to ensure protectiveness.
f. BNSF Railway: During excavation activities, it was determined that waste extends
across the shared property boundary with BNSF Railway; the exact extent is unknown.
Excavation in close proximity to the rail line is not recommended as this may alter the stability
and integrity of the slope and rail line construction; therefore, waste will be left on the BNSF
property. As such, backfill of the excavated areas and areas above the waste material provides
for slope control, drainage control, and establishment of vegetation. BNSF will place an
institutional control on the railroad right-of-way. Operation and maintenance activities will be
conducted by ODEQ in coordination with BNSF. Five-year reviews will be conducted by EPA
to ensure protectiveness.
Operation and Maintenance
Because waste will be left in place and the Site will be restricted to industrial use, operation and
maintenance (O&M) activities will be conducted by ODEQ and will be required to ensure
remedy protectiveness, no less often than once per year. O&M activities will include Site
inspections for erosion, property uses, and enforcement of the ICs. This activity may also
include maintenance of the slopes through grading, seeding, or importing of backfill that may be
needed. Maintenance of these slopes will provide continued slope support, continued drainage
control, and continued vegetation growth. Areas of primary interest will include the slopes along
Hwy 142, Atlas Roofing Inc., Oneok Gas Pipeline, BNSF Railway, and Valero Refining.
Institutional Controls
Because waste will be left in place and the Site will be restricted to industrial use, institutional
controls will be required. The purpose of this IC is to inform the general public of the restrictions
and circumstances of the Site so that the risk of exposure is minimized. In accordance with
Oklahoma Statutes, 27A § 2-7-123 (B), the ODEQ has the authority to file a Notice of
Remediation or Related Action Taken Pursuant to the Federal Comprehensive Environmental
Response, Compensation and Liability Act. This notice will identify the reason for notice, the
affected property, the remedy activities conducted on the Site, the engineering controls used on
the Site, continuing operation, maintenance and monitoring activities that will be conducted, and
the land use restrictions. This notice will also describe the proper management and disposal of
the material should construction activity within these areas be required. This notice will run
with the land and no change of ownership will change the land use restrictions. Any changes to
these restrictions will be proposed to ODEQ for review and if approved, ODEQ may remove or
alter the notice and land use restrictions. During O&M activities, these ICs will be reviewed to
ensure that the restrictions remain in place and that any Site activities adhere to these
restrictions.
Five-year Reviews
Because this remedy will result in hazardous substances, pollutants, or contaminants remaining
onsite above levels that allow for unlimited use and unrestricted exposure, a five-year review
will be required for this remedial action no less than every five years and will be conducted by
EPA in coordination with ODEQ. The purpose of the five-year review is to evaluate the Site
remedy for continued protectiveness. A Site inspection will be conducted to provide information
about Site status and to visually confirm and document the conditions of the remedy, the site,
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and the surrounding area. Observations will be made for any evidence of erosion, property uses,
trespass and vandalism and any corrective measures that were taken during operation and
maintenance. As Site condition and data warrant, sediment sampling may be conducted once
every five-years in order to evaluate the continued protectiveness of the sediment overburden.
Data and other pertinent Site-specific information will be reviewed to determine whether
maintenance procedures, as implemented, will maintain the effectiveness of response actions.
This will include review of sampling and monitoring plans, results from monitoring activities,
O&M reports, and previous five-year reviews.
In addition to Site-specific information, the original assumptions regarding current and future
land/groundwater uses and contaminants of concern will be reviewed to make sure that these are
still valid. Along with this, physical features and the understanding of physical Site conditions
will be reviewed for any changes that may effect changes in standards and assumptions that were
used at the time of remedy selection. The five-year review will also evaluate any changes in the
promulgated standards or “to be considered” standards as well as risk parameters that may
impact the protectiveness of the remedy.
Table 2: Comparisons of the Differences between the 2007 ROD and RA Construction
Component 2007 ROD RA Construction Difference
Soil Cleanup Levels Residential:
20 mg/kg arsenic
1.55 mg/kg benzo(a)pyrene
Industrial:
20 mg/kg arsenic
5.27 mg/kg benzo(a)pyrene
Residential Scenario
verses
Industrial Scenario
Soil and Waste
Volume
29,521 yd3 104,493.5 yd3 74,972.5 yd3 increase
Waste Left in Place All waste removed Waste left in Place Waste Left in Place
Institutional Controls No ICs ICs included No cost Difference
O&M (present value
cost estimated for 30
year time period)
No Cost
$119,532.57
$119,532.57 increase
Five-year Reviews
(present value cost
estimated for 30 year
time period)
No Cost
$59,598.90
$59,598.90 increase
Remedial Cost $4,390,141 $6,800,000 $2,409,859 increase
Pre-Final Inspections
The ODEQ and EPA conducted pre-final inspections on August 6, 2008, August 13, 2008, and
September 10, 2008.
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The following items were determined to be complete.
• Groundwater Monitoring Well Completion
• Clearing and Grubbing
• Excavation of waste and contaminated soil and sediment
• Offsite Disposal of waste and contaminated soil and sediment
• Surface water discharge
• Confirmation and Waste Profile Sampling
• Backfill, grading and seeding of the West Parcel
• Backfill, grading and seeding of the East Parcel
During the pre-final inspections, the ODEQ and EPA determined that the following punch-list
items remained:
• Operational and Functional Activities
• Final Inspection
• Filing of the Institutional Controls
III. Demonstration of Cleanup Activity Quality Assurance and Quality
Control
The EPA and ODEQ reviewed the remedial action contract and the construction work for
compliance with quality assurance and quality control (QA/QC) protocols. Construction
activities at the Site were determined to be consistent with the ROD and adhered to the approved
quality assurance plan which incorporated all EPA and State requirements. Confirmatory
inspections, independent testing, audits, and evaluations of materials and workmanship were
performed in accordance with the technical specifications and plans. The EPA Remedial Project
Manager and State regulators visited the site during construction activities to review construction
progress and evaluate and review the results of QA/QC activities. No deviations or non-adherence
to QA/QC protocols, or specifications were identified.
The quality assurance project plan incorporated all EPA and State QA/QC procedures and
protocols. All monitoring equipment was calibrated and operated in accordance with the
manufacturer’s instructions. The EPA analytical methods were used for all confirmation and
monitoring samples during RA activities. Contract laboratory program-like procedures and
protocol were followed for soil, sediments, and water analyses during the RA using a private
laboratory.
The EPA contract for the remedial action contained provisions for performing sampling during
all remedial activities in order to verify that remedial objectives were met, to ensure quality
control and assurance for all excavation and construction activity, and to ensure protection and
safety of the public, the environment, and the onsite worker. Non-hazardous wastes were sent to
the Waste Connection Landfill in Alex, Oklahoma. Sampling was conducted in accordance with
the Site Field Sampling Plan and all analytical results are below the established cleanup levels
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for an industrial reuse scenario. In addition, all backfill confirmation sample results met the
established cleanup levels for an industrial reuse scenario. All analytical data was independently
validated, and the EPA and the State determined that analytical results were accurate to the
degree needed to assure satisfactory execution of the RA.
IV. Activities and Schedule for Site Completion
The following activities will be completed according to the schedule presented in Table 3.
Table 3: Tasks to be Completed
Task Estimated Completion Responsible Organization
File ICs December 2008 ODEQ
Operational and Functional September 2009 EPA/ODEQ
Complete O&M Plan September 2009 ODEQ
Final Site Inspection September 2009 EPA/ODEQ
Complete Final RA Report September 2009 EPA/ODEQ
Final Close Out Report December 2009 EPA
1st Annual Inspection March 2009 EPA/ODEQ
2nd Annual Inspection March 2010 ODEQ
3rd Annual Inspection March 2011 ODEQ
4th Annual Inspection March 2012 ODEQ
Five-Year Review February 13, 2013 EPA
V. Summary of Remediation Costs
The original cost estimate to implement the remedial action described in the ROD was as
follows:
Capital Costs $4,390,141.14 (Present Worth)
O&M Costs $0.00 (Present Worth)
As presented in the ROD, these costs were calculated as order-of-magnitude engineering cost
estimates expected to be within +50 to -30 percent of actual project costs, discounted at 7 percent
to provide a present worth value suitable for comparison of the various remedial alternatives.
The estimated cost for implementation of the remedial action is as follows:
Actual Construction Costs $6,620,868.60 (Estimated)
O&M Costs $179,131.47 (Present Worth)
WA-K
DR-01
WA-L
WA-B
WA-F
WA-H
WA-I
WA-D
WA-C
WA-J
WA-E
WA-A PA-11
WA-G
Legend
Tar-mat Waste Area (WA-A)
Site Boundary
Process Area
Historical Road
Railroad
Drainage (DR1)
Drainage Flow Direction
310 155 0 310
Feet
-
Created 10/12/07
West Parcel
East Parcel
East RR Parcel
West Pond
East Pond
VTR8
VTR2
VTR5
VTR4
VTR14
VTR3
VTR1
VTR9
VTR11
VTR10 VTR15
VTR12
VTR6
VTR7 VTR13
UST
DR1
DR7
DR10
SAND CREEK
DR18
DR14
DR2
DR8
DR13
DR16
DR6
DR15
DR17
DR4
DR9
DR5
DR19
DR3
DAM
DR7
DR1
BURLINGTON, NORTHERN AND SANTA FE RAILROAD
STATE HIGHWAY 142
PROCESS AREAF
Figure 1 - Site Features
Imperial Refining Company
Vertical Tank Remenant (VTR1)
Created 10/16/07

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Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 1 of 13
Preliminary Close Out Report
Imperial Refining Superfund Site
Ardmore, Carter County, Oklahoma
(CERCLIS ID OK0002024099)
United States Environmental
Protection Agency
Region 6
Superfund Division
September 18, 2008
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 2 of 13
I. Introduction
The U.S. Environmental Protection Agency (EPA) has completed this Preliminary Close Out
Report for the Imperial Refining Superfund Site (Site) in accordance with the Close Out
Procedures for National Priorities List Sites, OSWER Directive 9320.2 – 09A-P, and in
recognition of the completion of the remedy construction consistent with the Record of Decision
(ROD). This determination is based on review of Site data, field inspections and oversight, and
three pre-final inspections (August 6, 2008; August 13, 2008; and September 10, 2008)
conducted by the Oklahoma Department of Environmental Quality (ODEQ) and the EPA. The
Site remedy construction was accomplished pursuant to, and in accordance with, the
requirements of the Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA), 42 U.S.C. § 9601 et seq., and consistent with the National Contingency Plan (NCP),
40 CFR Part 300. The EPA and ODEQ have initiated the activities necessary to achieve the
cleanup levels and site completion.
II. Summary of Site Conditions
Background
The Imperial Refining Company (IRC) Superfund Site is the location of a former petroleum
refinery that operated from 1917 to 1934. The legal description for the property is SE ¼, NE ¼,
Section 20, and SW ¼, NW ¼, Section 21, T4S, R2E, Indian Meridian, which is located within
the northeastern portion of the City of Ardmore, Carter County, Oklahoma. The IRC Site is
divided into three parcels: the West (36.5 acres), East (14.5 acres) and East Railroad (21 acres).
The Site covers approximately 72 acres and is bisected by U.S. Highway (Hwy) 142 and railroad
tracks operated by the BNSF Railway Company (Figure 1). Numerous tanks and buildings were
present on the Site during refinery operation, but all of the tanks and most of the buildings were
dismantled sometime between 1934 and 1948 leaving the property in much the same condition
as it is in today, mixed wooded areas and open fields.
The adjacent property to the north and east of Hwy 142 is occupied by a facility that
manufactures roofing shingles. Waste-water processing lagoons operated by Valero Refining are
located west of the Site, and the rest of the immediately adjacent property is largely
undeveloped. Several small businesses, Valero’s active refinery, and a small residential area with
about a dozen houses (along the streets of Brooks, Akron, Commerce and Industrial) are located
within ¼ mile north of the Site. An estimated 23,000 people live within a 4-mile radius of the
Site.
The IRC began operations at the Site in 1917. The eastern portion of the property was purchased
in April 1917, and the western portion was purchased three months later. IRC remained active
for 17 years until it went bankrupt in 1934. Due to the absence of environmental regulations
during the operational period of IRC, no permits, violations, inspections, or facility operation
documentation have been identified, and no records have been found that describe the types of
activities that took place on the Site. Currently, the land is privately owned, and no commercial
activities are taking place.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 3 of 13
Preliminary Investigations
The ODEQ conducted a Preliminary Assessment in September 1997 and a Site Inspection in July
1998. Based on the results, elevated levels of benzene, ethylbenzene, toluene, xylenes and
polycyclic aromatic hydrocarbons were present. ODEQ referred the property to the EPA for
further action.
Removal Actions
Subsequent to the ODEQ investigations, EPA conducted a Removal Assessment in 1998 to
determine the absence/presence of hazardous materials and the types and concentrations of
hazardous substances followed by a second Removal Assessment in 1999 to estimate waste pile
volumes and evaluate disposal options. A Removal Action to install a perimeter fence was
conducted from June 29, 2004, through July 23, 2004.
The Site was proposed to the NPL on May 11, 2000, [Federal Register: May 11, 2000 (Volume
65, No. 92, Page 30489-30495)] and was finalized on July 27, 2000 [Federal Register: July 27,
2000 (Volume 65, Number 145, Page 46096-46104)].
Remedial Investigation/Feasibility Study
The EPA and ODEQ negotiated a Cooperative Agreement under which the ODEQ was the lead
agency for the Remedial Investigation/Feasibility Study (RI/FS) with EPA acting as the
supporting agency. From early 2005 through early 2007, contractors for the ODEQ conducted a
RI/FS including field sampling and investigation activities of soil, sediment, surface water,
ground water, and animal tissue. The Remedial Investigation and Feasibility Study reports
identified the types, quantities, and locations of contaminants found in these samples and
developed ways to address the contamination. In addition, a Human Health Risk Assessment
and an Ecological Risk Assessment were performed to determine the current and future effects
of contaminants on human health and the environment.
Onsite contamination includes waste material, soil and sediment. Arsenic and benzo(a)pyrene
are the primary contaminants of concern. The primary sources of contaminants are waste in an
underground storage tank and waste piles characterized as dry, asphalt-like material. The waste
material is found throughout the Site, and the benzo(a)pyrene concentrations range from 2.5
milligram per kilogram (mg/kg) to 570 mg/kg. In addition to the waste material, surface soil [0-
1 foot (ft) below ground surface] and sediment (0-1 ft below ground surface) have elevated
concentrations of benzo(a)pyrene and arsenic. The soil concentrations range from 1 mg/kg to 90
mg/kg for arsenic and 0.04 mg/kg to 10.2 mg/kg for benzo(a)pyrene. Sediments in onsite
intermittent drainages are indistinguishable from Site soils except by their location within
drainages; therefore, the drainage sediments are considered soils for the remedial action as these
remain dry most of the year.
Record of Decision
After review and response to comments, the Record of Decision was signed on December 26,
2007. Remedial Action Objectives (RAOs) were developed for Site soil, sediment, and waste
material and are listed below.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 4 of 13
Surface Soil
• Prevent exposure to current and future human and ecological receptors through ingestion,
dermal contact, and inhalation of contaminated soil containing arsenic and benzo(a)pyrene
concentrations in excess of 5E-05 and 2.5E-05 excess cancer risk, respectively.
Pond and Creek Sediment
• Prevent exposure to current and future human receptors through ingestion, dermal contact, and
inhalation of contaminated sediment containing arsenic concentrations in excess of 5E-05 excess
cancer risk.
• Prevent exposure to current and future ecological receptors through direct contact, foodchain
uptake, and incidental ingestion of contaminated sediment containing benzo(a)pyrene
concentrations in excess of levels that are protective of ecological receptors.
Waste Material
• Prevent exposure to human and ecological receptors through ingestion and dermal contact.
• Prevent further migration of waste material contamination.
In order to achieve these RAOs, numerical risk-based cleanup levels were established for each
environmental medium based on the residential scenario:
The ROD addressed the Site as one operable unit where the final response action will address
Site contaminants and waste material through the following:
Table 1 – Cleanup Levels for Contaminants of Concern under a Residential Scenario
Media: Soil
Site Area: West and East Parcel
Available Use: Residential
Chemical of Cleanup Level Basis for Cleanup Level Risk at Cleanup Level
Concern
Arsenic 20 mg/kg Background level 5.00E-05
Benzo(a)pyrene 1.55 mg/kg Human Health Risk
Assessment 2.50E-05
Media: Sediment
Site Area: East and West Ponds, Sand Creek
Available Use: Residential
Chemical of Cleanup Level Basis for Cleanup Level Risk at Cleanup Level
Concern
Arsenic 20 mg/kg Background level 5.00E-05
Benzo(a)pyrene 0.782 mg/kg Ecological Risk Assessment
Invertebrate Toxicity Test
N/A
Results
Note: mg/kg: milligrams per kilogram
N/A: Not Applicable
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 5 of 13
• 13,083 yd3 of waste material will be removed and disposed offsite at an appropriately regulated
facility based on results from toxicity characteristic leaching procedure (TCLP) analyses. This
addresses the principal threat waste at the Site.
• 16,438 yd3 of arsenic and benzo(a)pyrene contaminated soil will be excavated and disposed
offsite at an appropriately regulated facility based on results from TCLP analyses.
• 1,633 yd3 of arsenic and benzo(a)pyrene contaminated sediment will be excavated and disposed
offsite at an appropriately regulated facility based on results from TCLP analyses.
The remedial action set forth in the ROD was consistent with, and complied with, the Superfund
Amendments and Reauthorization Act (SARA) of 1986, P.L. 99-499, which substantially
amended CERCLA, 42 U.S.C. § 9601 et seq., and the NCP. SARA codified many of the
existing requirements under the then existing NCP (1985), as well as adding, among other
things, a new Section 121 to CERCLA, which provided direction for selection of remedial
actions compliant with applicable or relevant and appropriate Federal, State, and Local laws
regulations and requirements, 42 U.S.C. § 9621.
Based on the investigation of Site historical information, one potentially responsible party (PRP)
was identified. EPA and the PRP negotiated and signed an Administrative Order on Consent
based on Ability-to-Pay Analysis (September 15, 2004). The Site remedial action was completed
as an EPA fund-lead project, with the ODEQ as the support Agency.
Remedial Design
A detailed remedial design was not performed due the simplicity of the selected remedy. A
value engineering evaluation and the remedial design and remedial action work plan were
completed on January 30, 2008. During work plan development, additional field activity was not
considered necessary as the extent of waste was presumed to be known.
Remedial Construction Activities
The EPA began onsite RA construction February 13, 2008. As excavation of the waste material
began and continued into the following weeks, it became clear that the vertical and horizontal
extents were understated, and the original volume estimate was low. Although, the expectation
was to exceed the original volume estimate, attempts were made to meet the residential cleanup
values. As excavation activities progressed, waste was found to exist in locations where removal
would be both impracticable and dangerous. Due to the increase in horizontal and vertical extent,
increase in volume, and locations where waste will be left in place, aspects of the original
remedy were reevaluated and are described below. These changes will be documented in a
Record of Decision-Amendment.
Cost
The original cost estimate to implement the remedial action described in the ROD was $4.4
million (net present worth). Costs were estimated at a discount rate of 7% with no operation and
maintenance (O&M) or five-year reviews. Due to the increase in waste volume, a revised cost
estimate for the project is projected to be $6.8 million. The difference between the ROD
estimate and the revised cost estimate is due to the increased costs associated with the increased
volume of waste material excavated and disposed offsite as well as the inclusion of backfill
material necessary for Site restoration and grading. In addition, five-year reviews and O&M will
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 6 of 13
be required and the estimated cost, projected for a timeframe of 30 years is $179,131.47. A
complete breakdown of the final costs and details related to O&M activities will be presented in
the final Remedial Action Report and the final O&M Plan.
Volume
Refinery wastes were encountered at depths up to 10 feet below ground surface and in locations
not previously identified during the Remedial Investigation. Therefore, the discovery and
excavation of these new locations increased the volume of waste material disposed. Because
these were defined as principal threat wastes, excavation and disposal was necessary to eliminate
the wastes as a source of contamination for soil, sediment, surface water, and ground water as
well as eliminate the threat to human health and the environment. It is expected that the volume
of material excavated and disposed offsite will reach an estimated 104,493.5 cubic yards
(yd3)/105,770.76 tons which represents an increase of 74,972.5 yd3/55,954.76 tons over the
estimated 29,521 yd3/49,816 tons presented in the December 26, 2007, Record of Decision
(ROD). A complete breakdown of the final volume will be presented in the final Remedial
Action Report.
Cleanup Values
The cleanup scenario presented in the ROD is based on the child resident. When the industrial
and residential soil scenarios were compared, it was noted that cleanup to a residential scenario
minimally increased soil volume (690 yd) and cost ($252,068); it would result in unlimited use
and unrestricted exposure; and would be protective for all other human and terrestrial ecological
receptors. Therefore, in order to be protective for Site reuse under a residential scenario and
meet the RAOs, cleanup levels in the ROD were established for the primary contaminants of
concern, arsenic (5E-05 excess lifetime cancer risk) and benzo(a)pyrene (2.5E-05 excess lifetime
cancer risk).
The widespread extent, depth, and location of the waste material discovered across the Site
during the remedial action have made excavation impracticable and potentially dangerous in
some areas. Because of this, waste material will be left in place (see sub-section Waste Left in
Place), which makes the residential scenario no longer suitable for this Site.
Current and future zoning maps produced by the City of Ardmore depict portions of the Site
west of Hwy 142 and east of the railroad tracks as light industrial and the portion of the Site east
of Hwy 142 and west of the railroad tracks as heavy industrial. The human health risk
assessment evaluated risk for the industrial worker and showed that the excess lifetime cancer
risk for an industrial worker fell within the risk range of 1E-04 to 1E-06 and the non-carcinogenic
risk was less than 1. The excess lifetime cancer risk is primarily associated with
the ingestion and dermal contact pathways related to arsenic and benzo(a)pyrene in the soil and
sediment. Because the exposure pathways and contaminants of concern are the same as those
identified for the future child resident, the RAOs presented in the ROD remain unchanged.
Therefore, changing from a residential scenario to an industrial scenario is protective, and in
order to meet the RAOs under an industrial scenario, revised cleanup levels were established.
In the absence of Federal or State cleanup standards for soil contamination, the Site cleanup
levels are based on the baseline risk assessment. The arsenic cleanup level remains set at 20
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 7 of 13
mg/kg which is within the range for Oklahoma background soils, represents an excess upper
bound lifetime cancer risk to an individual of 5E-05 which is within EPA’s cancer risk range of
1E-06 to 1E-04, is below the non-cancer benchmark of 1, and is considered protective of human
health and the environment. Using all assumptions and calculations presented in the human
health risk assessment, the cleanup level for benzo(a)pyrene (2.5E-05 excess lifetime cancer
risk) under an industrial reuse scenario is 5.27 mg/kg, and is considered protective of human
health and the environment. Despite the change in the cleanup level, these risk drivers remain
co-located with other metals and organics as well as areas of ecological risk associated with the
upland habitat (soil) and wet areas (sediment not in the ponds or creek); therefore, revision of the
ecological cleanup levels is not necessary.
Because the Site will be restricted to industrial use and is not available for unlimited use and
unrestricted exposure, institutional controls, O&M, and five-year reviews will be required.
These activities are applicable to the entire Site. Details related to these activities are described
below.
Waste Left in Place
The widespread extent, depth, and location of the waste material discovered across the Site
during the remedial action have made excavation impracticable and potentially dangerous in
some areas. Excavation and removal activities have progressed to the extent practicable;
however, there will be areas where waste remains. This material has been identified as a non-hazardous
waste. In addition, TCLP data indicate that the leaching potential of this material is
low as all results have been below regulatory limits for characteristic hazardous waste categories
and land disposal restrictions. As such, backfill of the excavated areas and areas above the waste
material provides for slope control, drainage control, and establishment of vegetation.
a. Ponds: All surface sediments that exceeded the ecological cleanup level have been
excavated and confirmation samples have been collected. The confirmation sample results are
below the ecological cleanup level. Based on excavation activities along the drainages and shore
lines, waste was documented at depths greater than 18 inches and extending out into the ponds.
Additional delineation pits were excavated within the east and west ponds to identify the extent
of the waste. The delineation pits indicated that the waste is widespread and continued to be
present under at least 18 inches of uncontaminated overburden. The presence of the overburden
and its thickness is expected to act as a barrier between the waste and the surface sediments as
well as provide ample non-contaminated burrowing material above the waste for benthic
invertebrates. This is supported by the surface sediment results from the remedial investigation
and those confirmation samples collected during the remedial action. In addition, erosion and
scouring of the overburden is not expected as these ponds are stagnant for most of the year and
high flow velocity currents are rare. Due to the presence of uncontaminated overburden, the
complete removal of surface sediment exceeding the ecological cleanup numbers, and the
unknown locations of waste at depth throughout the remaining areas of the ponds, no further
excavation will occur. Excavated areas will be backfilled with clean material and an institutional
control (IC) will be placed on the ponds. Operation and maintenance activities will be conducted
by ODEQ and five-year reviews will be conducted by EPA to ensure protectiveness.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 8 of 13
b. Northern boundary with Atlas Roofing: The northern boundary of the eastern parcel is a
slope approximately 10 to 15 feet in height. Atlas Roofing, Inc., is built on the land at the top of
this slope. Excavation activities along this border indicate that waste materials extend into this
slope; the exact extent is unknown. Excavation and removal of waste along this border is not
feasible or practical as this may alter the stability and integrity of the slope. An engineering
evaluation identified suitable slope stabilization and construction activities and an appropriate
backfill material for placement on the waste. A slope of no greater than 3 feet vertical to 1 foot
horizontal will be maintained along this border to minimize erosion and facilitate slope support,
drainage control, and re-vegetation. Atlas Roofing will place an institutional control on the Atlas
Roofing, Inc., property. Operation and maintenance activities on the slope will be conducted by
ODEQ in coordination with Atlas Roofing, Inc. Five-year reviews will be conducted by EPA to
ensure protectiveness.
c. Hwy 142: The situation is similar to the northern border with Atlas Roofing, Inc. The
highway sits atop a slope approximately 10 to 15 feet in height. Excavation activities along the
eastern and western borders of Hwy 142 indicate that waste materials extend into this slope and
under the highway exposing itself on the opposite side. Excavation and removal of waste along
these borders and under the highway is not feasible or practical as this may alter the stability and
integrity of the slope and the highway. An engineering evaluation identified suitable slope
stabilization and construction activities and backfill material for placement on the waste. A
slope of no greater than 3 feet vertical to 1 foot horizontal will be maintained along this border to
minimize erosion and facilitate slope support, drainage control, and re-vegetation. The
Oklahoma Department of Transportation (ODOT) will place an institutional control on Hwy 142
and its associated utility easements. Operation and maintenance activities on the slope will be
conducted by ODEQ in coordination with ODOT. Five-year reviews will be conducted by EPA
to ensure protectiveness.
d. Northern and Western Boundary with Valero Refinery property: During excavation
activities, it was determined that waste extends across the shared western and northern property
boundaries with Valero Refinery. ODEQ’s Resource Conservation and Recovery Act (RCRA)
section will be working with Valero Refinery to address the waste along these borders. Backfill
of the excavated areas and areas above the waste material provides for slope control, drainage
control, and establishment of vegetation. The drainage along this boundary will be re-directed
away from these waste areas in an effort to mitigate erosion, ensure drainage control, and
facilitate re-vegetation. Operation and maintenance activities on the Imperial Refinery side of the
property will be conducted by ODEQ. Five-year reviews will be conducted by EPA to ensure
protectiveness.
e. Oneok Gas Line: Excavation in close proximity to the high pressure gas line was not
recommended or considered safe; therefore, waste was left around the gas line and within the
easement boundaries. Clay backfill was placed on either side of the pipeline and a depth of
approximately two feet, was placed along the top of the gas line to provide a barrier for the
pipeline and promote surface water runoff. A gentle slope will be maintained along this border
to minimize erosion and facilitate slope support, drainage control, and re-vegetation. An
institutional control will be placed on the Oneok easement as part of the Imperial Refining Site.
Operation and maintenance activities will be conducted by ODEQ in coordination with Oneok.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 9 of 13
Five-year reviews will be conducted by EPA to ensure protectiveness.
f. BNSF Railway: During excavation activities, it was determined that waste extends
across the shared property boundary with BNSF Railway; the exact extent is unknown.
Excavation in close proximity to the rail line is not recommended as this may alter the stability
and integrity of the slope and rail line construction; therefore, waste will be left on the BNSF
property. As such, backfill of the excavated areas and areas above the waste material provides
for slope control, drainage control, and establishment of vegetation. BNSF will place an
institutional control on the railroad right-of-way. Operation and maintenance activities will be
conducted by ODEQ in coordination with BNSF. Five-year reviews will be conducted by EPA
to ensure protectiveness.
Operation and Maintenance
Because waste will be left in place and the Site will be restricted to industrial use, operation and
maintenance (O&M) activities will be conducted by ODEQ and will be required to ensure
remedy protectiveness, no less often than once per year. O&M activities will include Site
inspections for erosion, property uses, and enforcement of the ICs. This activity may also
include maintenance of the slopes through grading, seeding, or importing of backfill that may be
needed. Maintenance of these slopes will provide continued slope support, continued drainage
control, and continued vegetation growth. Areas of primary interest will include the slopes along
Hwy 142, Atlas Roofing Inc., Oneok Gas Pipeline, BNSF Railway, and Valero Refining.
Institutional Controls
Because waste will be left in place and the Site will be restricted to industrial use, institutional
controls will be required. The purpose of this IC is to inform the general public of the restrictions
and circumstances of the Site so that the risk of exposure is minimized. In accordance with
Oklahoma Statutes, 27A § 2-7-123 (B), the ODEQ has the authority to file a Notice of
Remediation or Related Action Taken Pursuant to the Federal Comprehensive Environmental
Response, Compensation and Liability Act. This notice will identify the reason for notice, the
affected property, the remedy activities conducted on the Site, the engineering controls used on
the Site, continuing operation, maintenance and monitoring activities that will be conducted, and
the land use restrictions. This notice will also describe the proper management and disposal of
the material should construction activity within these areas be required. This notice will run
with the land and no change of ownership will change the land use restrictions. Any changes to
these restrictions will be proposed to ODEQ for review and if approved, ODEQ may remove or
alter the notice and land use restrictions. During O&M activities, these ICs will be reviewed to
ensure that the restrictions remain in place and that any Site activities adhere to these
restrictions.
Five-year Reviews
Because this remedy will result in hazardous substances, pollutants, or contaminants remaining
onsite above levels that allow for unlimited use and unrestricted exposure, a five-year review
will be required for this remedial action no less than every five years and will be conducted by
EPA in coordination with ODEQ. The purpose of the five-year review is to evaluate the Site
remedy for continued protectiveness. A Site inspection will be conducted to provide information
about Site status and to visually confirm and document the conditions of the remedy, the site,
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 10 of 13
and the surrounding area. Observations will be made for any evidence of erosion, property uses,
trespass and vandalism and any corrective measures that were taken during operation and
maintenance. As Site condition and data warrant, sediment sampling may be conducted once
every five-years in order to evaluate the continued protectiveness of the sediment overburden.
Data and other pertinent Site-specific information will be reviewed to determine whether
maintenance procedures, as implemented, will maintain the effectiveness of response actions.
This will include review of sampling and monitoring plans, results from monitoring activities,
O&M reports, and previous five-year reviews.
In addition to Site-specific information, the original assumptions regarding current and future
land/groundwater uses and contaminants of concern will be reviewed to make sure that these are
still valid. Along with this, physical features and the understanding of physical Site conditions
will be reviewed for any changes that may effect changes in standards and assumptions that were
used at the time of remedy selection. The five-year review will also evaluate any changes in the
promulgated standards or “to be considered” standards as well as risk parameters that may
impact the protectiveness of the remedy.
Table 2: Comparisons of the Differences between the 2007 ROD and RA Construction
Component 2007 ROD RA Construction Difference
Soil Cleanup Levels Residential:
20 mg/kg arsenic
1.55 mg/kg benzo(a)pyrene
Industrial:
20 mg/kg arsenic
5.27 mg/kg benzo(a)pyrene
Residential Scenario
verses
Industrial Scenario
Soil and Waste
Volume
29,521 yd3 104,493.5 yd3 74,972.5 yd3 increase
Waste Left in Place All waste removed Waste left in Place Waste Left in Place
Institutional Controls No ICs ICs included No cost Difference
O&M (present value
cost estimated for 30
year time period)
No Cost
$119,532.57
$119,532.57 increase
Five-year Reviews
(present value cost
estimated for 30 year
time period)
No Cost
$59,598.90
$59,598.90 increase
Remedial Cost $4,390,141 $6,800,000 $2,409,859 increase
Pre-Final Inspections
The ODEQ and EPA conducted pre-final inspections on August 6, 2008, August 13, 2008, and
September 10, 2008.
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 11 of 13
The following items were determined to be complete.
• Groundwater Monitoring Well Completion
• Clearing and Grubbing
• Excavation of waste and contaminated soil and sediment
• Offsite Disposal of waste and contaminated soil and sediment
• Surface water discharge
• Confirmation and Waste Profile Sampling
• Backfill, grading and seeding of the West Parcel
• Backfill, grading and seeding of the East Parcel
During the pre-final inspections, the ODEQ and EPA determined that the following punch-list
items remained:
• Operational and Functional Activities
• Final Inspection
• Filing of the Institutional Controls
III. Demonstration of Cleanup Activity Quality Assurance and Quality
Control
The EPA and ODEQ reviewed the remedial action contract and the construction work for
compliance with quality assurance and quality control (QA/QC) protocols. Construction
activities at the Site were determined to be consistent with the ROD and adhered to the approved
quality assurance plan which incorporated all EPA and State requirements. Confirmatory
inspections, independent testing, audits, and evaluations of materials and workmanship were
performed in accordance with the technical specifications and plans. The EPA Remedial Project
Manager and State regulators visited the site during construction activities to review construction
progress and evaluate and review the results of QA/QC activities. No deviations or non-adherence
to QA/QC protocols, or specifications were identified.
The quality assurance project plan incorporated all EPA and State QA/QC procedures and
protocols. All monitoring equipment was calibrated and operated in accordance with the
manufacturer’s instructions. The EPA analytical methods were used for all confirmation and
monitoring samples during RA activities. Contract laboratory program-like procedures and
protocol were followed for soil, sediments, and water analyses during the RA using a private
laboratory.
The EPA contract for the remedial action contained provisions for performing sampling during
all remedial activities in order to verify that remedial objectives were met, to ensure quality
control and assurance for all excavation and construction activity, and to ensure protection and
safety of the public, the environment, and the onsite worker. Non-hazardous wastes were sent to
the Waste Connection Landfill in Alex, Oklahoma. Sampling was conducted in accordance with
the Site Field Sampling Plan and all analytical results are below the established cleanup levels
Preliminary Close Out Report for Imperial Refining Superfund Site September 18, 2008
Page 12 of 13
for an industrial reuse scenario. In addition, all backfill confirmation sample results met the
established cleanup levels for an industrial reuse scenario. All analytical data was independently
validated, and the EPA and the State determined that analytical results were accurate to the
degree needed to assure satisfactory execution of the RA.
IV. Activities and Schedule for Site Completion
The following activities will be completed according to the schedule presented in Table 3.
Table 3: Tasks to be Completed
Task Estimated Completion Responsible Organization
File ICs December 2008 ODEQ
Operational and Functional September 2009 EPA/ODEQ
Complete O&M Plan September 2009 ODEQ
Final Site Inspection September 2009 EPA/ODEQ
Complete Final RA Report September 2009 EPA/ODEQ
Final Close Out Report December 2009 EPA
1st Annual Inspection March 2009 EPA/ODEQ
2nd Annual Inspection March 2010 ODEQ
3rd Annual Inspection March 2011 ODEQ
4th Annual Inspection March 2012 ODEQ
Five-Year Review February 13, 2013 EPA
V. Summary of Remediation Costs
The original cost estimate to implement the remedial action described in the ROD was as
follows:
Capital Costs $4,390,141.14 (Present Worth)
O&M Costs $0.00 (Present Worth)
As presented in the ROD, these costs were calculated as order-of-magnitude engineering cost
estimates expected to be within +50 to -30 percent of actual project costs, discounted at 7 percent
to provide a present worth value suitable for comparison of the various remedial alternatives.
The estimated cost for implementation of the remedial action is as follows:
Actual Construction Costs $6,620,868.60 (Estimated)
O&M Costs $179,131.47 (Present Worth)
WA-K
DR-01
WA-L
WA-B
WA-F
WA-H
WA-I
WA-D
WA-C
WA-J
WA-E
WA-A PA-11
WA-G
Legend
Tar-mat Waste Area (WA-A)
Site Boundary
Process Area
Historical Road
Railroad
Drainage (DR1)
Drainage Flow Direction
310 155 0 310
Feet
-
Created 10/12/07
West Parcel
East Parcel
East RR Parcel
West Pond
East Pond
VTR8
VTR2
VTR5
VTR4
VTR14
VTR3
VTR1
VTR9
VTR11
VTR10 VTR15
VTR12
VTR6
VTR7 VTR13
UST
DR1
DR7
DR10
SAND CREEK
DR18
DR14
DR2
DR8
DR13
DR16
DR6
DR15
DR17
DR4
DR9
DR5
DR19
DR3
DAM
DR7
DR1
BURLINGTON, NORTHERN AND SANTA FE RAILROAD
STATE HIGHWAY 142
PROCESS AREAF
Figure 1 - Site Features
Imperial Refining Company
Vertical Tank Remenant (VTR1)
Created 10/16/07